note that many anatomy ontologies consider this synonymous with digestive system. here we follow MA in dividing digestive system into gastrointestinal and hepatobiliary. hepatobiliary includes the liver and biliary tract. species-specific AO classes are categorized according to whether liver is included. For example, XAO includes liver as part of XAO:0000125 alimentary system, so we assume this class is the more generic class. We have one entity that is part of both gastrointestinal and hepatobiliary systems: hepatopancreatic ampulla

Ontology associationEach term has an is_a parent in the Uberon Ontology, which has a linkage to an another entity and FANTOM5 samples.Libraries were grouped into mutually exclusive facets according to the FANTOM5 sample ontology mapping to UBERON ontologies.